Rear-End Impacts – Part 1: Field and Test Data Analysis of Crash Characteristics
2022-01-1041
03/29/2022
- Event
- Content
- Prior to developing or modifying the protocol of performance evaluation tests, it is important to identify field relevant conditions. The objective of this study was to assess the distribution of selected crash variables from rear crash field accidents involving modern vehicles. The exposure and serious-to-fatal injury of non-ejected occupants was determined in 2008+ model year (MY) vehicles using 2007-2015 NASS-CDS and 2017-2019 CISS. In addition, 15 EDRs were collected from 2017 to 2019 CISS cases with a rear delta V ranging from 32 to 48 km/h. Ten rear crash tests were also investigated to identifying pulse characteristics in rear crashes. The tests included five vehicle-to-vehicle crash tests and five FMVSS 301R barrier tests matching the struck vehicle. The analysis of NASS-CDS and CISS data indicates that more than 50% of exposed (MAIS 0+F) occupants were involved in a rear crash with a distributed impact and with no over-ride or under-ride. More than 93% were with a 6 o’clock PDOF. The average rear delta V was 21.3 ± 1.2 km/h in the exposed (MAIS 0+F) occupant sample. For serious-to-fatally (MAIS 3+F) injured occupants, more than 88% were in a fully distributed rear impact and in 6 o’clock PDOF; 10.7% were in offset impacts and less than 1% were in narrow impacts. The average delta V was 35.9 ± 5.2 km/h for serious-to-fatally (MAIS 3+F) injured occupants. The results from the field data suggest that rear impacts with a delta V of 34-38 km/h and a 6 o’clock PDOF are representative of the average rear-crash scenario causing serious-to-fatal injury. Compared to the exposed occupants in the field data analysis, a 40 km/h rear sled is more than 1.9-times more severe than the average rear impact crash severity in terms of delta V and 4.4-times more severe in terms of crash energy. It is 1.11-times more severe than the average delta V for the serious-to-fatally (MAIS 3+F) injured occupant. It accounts for more than 90% of all occupants with injury (MAIS 1+F). EDR data was helpful in providing overall velocity and impact duration information. For example, the average delta V in the EDRs included in the analysis was 38.7 ± 7.6 km/h and the average pulse duration was 129.6 ± 24.3 ms. Instrumentation data from crash tests provide more refined information for a detailed analysis of pulse characteristics. The acceleration data obtained from the five vehicle-to-vehicle crash tests was investigated and compared to matched FMVSS 301 tests with the same struck vehicle. The data was scaled to a 40 km/h delta V pulse. Bi-modal pulse shape characteristics were observed. The peak acceleration averaged 14 g in the vehicle-to-vehicle tests and 13 g in the FMVSS 301R tests. The average pulse duration was shorter in the FMVSS 301R tests than in the vehicle-to-vehicle crash tests, at 124 ms and 148 ms respectively. The results from this study suggest that using a 34-40 km/h bimodal-rear pulse with a 130-160 ms duration is representative of a serious real world rear impact.
- Citation
- Parenteau, C., White, S., Burnett, R., Stephens, G. et al., "Rear-End Impacts – Part 1: Field and Test Data Analysis of Crash Characteristics ," SAE Technical Paper 2022-01-1041, 2022, .